Biology, Eighth Edition (Raven)

Chapter 19: Cellular Mechanisms of Development

Pre Test

True or False: The overt differences of organism body plans suggest multiple mechanisms of development that evolved very recently in the history of multicellular life. (p. 370)
In what way(s) is/are the adult frog cell division different from cell divisions of its cells in the early blastomere stage? (p. 371)
A)There is almost no G1 stage in the blastomere cell cycle.
B)There is almost no G2 stage in the adult cell cycle.
C)Cyclin is not involved in regulating cell divisions in the blastomere cells.
D)The zygote does not contain much mRNA for cyclin.
E)All of the above are legitimate differences between adult and blastomere cell cycles.
How is therapeutic cloning different from reproductive cloning if applied to the elimination of genetic disease? (p. 379)
A)Reproductive cloning bypasses the genotypic influence of the afflicted parent, while therapeutic cloning leaves much of the patient's gene in place.
B)Therapeutic cloning allows the creation of clumps of tissue which are transferred to the patient, while reproductive cloning results in a new individual.
C)Both result in new individuals, but therapeutic cloning creates more stable insertion of genes into the genome of cells from the afflicted patient.
D)Only a and b correctly distinguish the techniques.
E)All of the above demonstrate differences between these techniques.
All animals (sponges, insects, primates, etc.) all contain Hox or Hox-like genes which stimulate developmental patterns. These are all absent from plants and fungi. What is the most likely explanation for the prevalence of these genes and gene clusters in the animal evolutionary line? (p. 386)
A)Because animals are the only creatures which show bilateral body plans, these genes are required for their proper development.
B)The presence of a Hox gene is necessary and sufficient for the establishment of an animal lifestyle.
C)Because more complex body plans are associated with clusters of Hox genes and evolution requires increasing complexity, these genes are selected for naturally.
D)An organism line which is ancestral to contemporary animals benefited from the developmental regulation afforded from the Hox genes, and these benefits have persisted through evolutionary time.
E)All of the above are plausible explanations.
If apoptosis was blocked in human development, which of the following might most likely occur? (p. 388)
A)The brain would become larger and more complex.
B)The dorsal/ventral axis would fail to develop properly.
C)Embryonic stem cells would differentiate more quickly.
D)Assymetric cell divisions would occur less frequently.
E)Webbed fingers and toes might be seen in the newborn.
How might temperature changes affect sex ratios of organisms? (p. 392)
A)Temperature changes have been shown to cause unpacking of genetic information, leading to restoration of cell totipotency.
B)Environmental cues can stimulate different programs in the embryos, leading to different developmental fates.
C)High temperature can lead to loss of male genes in the embryos, resulting in establishment of a default "female" genetic program.
D)All of the above influence sex ratios.
E)None of the above can influence sex ratios.
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